30 juillet 2013 2 30 /07 /juillet /2013 15:56
Dynamics of connective-tissue localization during chronic Borrelia burgdorferi infection Laboratory Investigation 93, 900-910 (August 2013) | doi:10.1038/labinvest.2013.81 Denise M Imai, Sunlian Feng, Emir Hodzic and Stephen W Barthold The etiologic agent of Lyme disease, Borrelia burgdorferi, localizes preferentially in the extracellular matrix during persistence. In chronically infected laboratory mice, there is a direct association between B. burgdorferi and the proteoglycan decorin, which suggests that decorin has a role in defining protective niches for persistent spirochetes. In this study, the tissue colocalization of B. burgdorferi with decorin and the dynamics of borrelial decorin tropism were evaluated during chronic infection. Spirochetes were found to colocalize absolutely with decorin, but not collagen I in chronically infected immunocompetent C3H mice. Passive immunization of infected C3H-scid mice with B. burgdorferi-specific immune serum resulted in the localization of spirochetes in decorin-rich microenvironments, with clearance of spirochetes from decorin-poor microenvironments. In passively immunized C3H-scid mice, tissue spirochete burdens were initially reduced, but increased over time as the B. burgdorferi-specific antibody levels waned. Concurrent repopulation of the previously cleared decorin-poor microenvironments was observed with the rising tissue spirochete burden and declining antibody titer. These findings indicate that the specificity of B. burgdorferi tissue localization during chronic infection is determined by decorin, driven by the borrelia-specific antibody response, and fluctuates with the antibody response. NB: Infusion of decorin into experimental rodent spinal cord injuries has been shown to suppress scar formation and promote axon growth. Decorin has been shown to have anti-tumorigenic properties in an experimental murine tumor model and is capable of suppressing the growth of various tumor cell lines. There are multiple alternatively spliced transcript variants known for the decorin gene. Mutations in the decorin gene are associated with congenital stromal corneal dystrophy.